Apparatus for applying an elastomeric sheath to a wireline used in oilfield service operations

ABSTRACT

A slotted, continuous elastomeric sheath is applied to a wireline as the wireline and its instruments connected thereto are lowered into a plastic lined tubing within an earth borehole, the elastomeric sheath being used to prevent damage to the plastic coating on the interior of the tubing. The tubular elastomeric sheath is wound on a storage drum for transportation and the application of the sheath to the wireline. The sheath passes through a measuring sheave having a throat positioned at the wireline to be covered. As the sheath approaches the wireline, an orienting finger is used within the slot in the sheath causing the slot to open up. The opening also results from a natural consequence of the sheath being bent about a radius with the slot in the sheath oriented to the outside of the sheave throat. Idler rollers are provided to facilitate the alignment of the sheath with the wireline. The measuring sheave is also used to monitor the linear velocity of the sheath as it is being removed from the wireline. The linear velocity of the wireline is also monitored and compared with the velocity of the sheath. An electrical comparator circuit drives a variable speed motor to either increase or decrease the velocity of the sheath to provide a means for removing the sheath from the wireline at the same velocity as the wireline as it is being hoisted from the well bore. During the application of the sheath to the wireline, the drum upon which the sheath is wound is allowed to rotate freely without the use of the motor and the sheath pulled off the drum by the frictional forces between the sheath and the wireline.

United States Patent Bohn Mar. 5 1974 1 APPARATUS FOR APPLYING AN ELASTOMERIC SHEATH TO A WIRELINE USED IN OILFIELD SERVICE OPERATIONS Floyd 0. Bohn, Houston, Tex. Dresser Industries, Inc., Dallas, Tex.

Oct. 25, 1972 [75] Inventor:

Assignee:

Filed:

Appl. No.:

References Cited UNITED STATES PATENTS 3/1965 Meeker et al 29/453 10/1952 Stone 29/200 D Primary Examiner--James A. Leppink Attorney, Agent, or FirmWilliam E. Johnson, Jr.

[57] ABSTRACT A slotted, continuous elastomeric sheath is applied to a wireline as the wireline and its instruments connected thereto are lowered into a plastic lined tubing TRANSMlSSlON within an earth borehole, the elastomeric sheath being used to prevent damage to the plastic coating on the interior of the tubing. The tubular elastomeric sheath is wound on a storage drum for transportation and the application of the sheath to the wireline. The sheath passes through a measuring sheave having a throat positioned at the wireline to be covered. As the sheath approaches the wireline, an orienting finger is used within the slot in the sheath causing the slot to open up. The opening also results from a natural consequence of the sheath being bent about a radius with the slot in the sheath oriented to the outside of the sheave throat. Idler rollers are provided to facilitate the alignment of the sheath with the wireline. The measuring sheave is also used to monitor the linear velocity of the sheath as it is being removed from the wireline. The linear velocity of the wireline is also monitored and compared with the velocity of the sheath. An electricalcomparator circuit drives a variable speed motor to either increase or decrease the velocity of the sheath to provide a means for removing the sheath fromthe wireline at the same velocity as the wireline as it is being hoisted from the well bore. During the application of the sheath to the wireline, the drum upon which the sheath is wound is allowed to rotate freely without the use of the motor and the sheath pulled off the drum by the frictional forces between the sheath and the wireline.

VELOCITY SENSOR ELECTRONICS RECORDER SHEET 1 BF 2 FIG. I

N w m M M. P. B w W 57 m T w\\\\\\\ 5 m PATENTED 74 PATENTEDHAR 3.1951275 SHEET 2 UF 2 ELECTRONICS RECORDER TRANSMISSION VELOCITY SENSOR COMPARATOR APPARATUS FOR APPLYING AN ELASTOMERIC SHEATI-I TO A WIRELINE USED IN OILFIELD SERVICE OPERATIONS BACKGROUND OF THE INVENTION This invention relates generally to the improvement of wireline oilfield service operations, and in particular, to method and apparatus for applying an elastomeric sheath to a wireline as it is being lowered into an earth borehole, especially within a tubing string, and having means for removing such sheath as the wireline is being retrieved from the well.

It is well known in the art of oil and gas well production that the metal tubing in such wells is frequently coated with plastic or plastic-like materials to prevent erosion to the metal. Furthermore, those in the art have evendone some work on using plastic as the tubing itself. In either event, it is often necessary to provide wireline services through such tubing, such as logging and perforating services, to name but two examples, and when using metallic wirelines to provide such services, the wireline will frequently damage the plastic on the tubing as the wireline is being lowered or raised through the tubing.

Those in the art,'in realizing that the plastic film on the tubing string will probably be damaged by the tools and the wirelines upon which the tools are run, have attempted to put elastomeric materials on the wireline in various ways, for example, by applying a'permanent elastomeric coating to the wireline cable. This has not proved to be practical, particularly on the length of cable required for even normal depth within the well bore. The tension on the wireline, due to its own weight as well as that of the tools on the end of the line, imposes considerable forces on the elastomeric coating, especially where the line is spooled on a hoisting drum and where the-line passes over sheaves required in the operation. The plastic coating on such wirelines known in the prior art have generally been cut, squeezed and otherwise damaged so quickly that such coatings have not been economically feasible.

It is therefore the primary object of the present invention to provide a new and improved method and apparatus for applying an elastomeric sheath around a wireline as it is being used in oilfield service operations;

It is also an object of the present invention to provide new and improved method and apparatus for conduct- It is yet another object of the present invention to provide a new and improved method and apparatus for removing an elastomeric sheath from a wireline as the wireline is being retrieved from an earth borehole.

The objects of the invention are accomplished, generally, by method and apparatus which applies a split elastomeric sheath to a wireline as the wireline is being lowered into an earth borehole. Means are also provided for removing the elastomeric sheath from the wireline as the wireline is being retrieved from the earth borehole.

These and other objects, features and advantages of the present invention will be more readily understood from a reading of the following detailed specification and drawing, in which:

FIG. 1 is an elevational view, partly in cross section, of a wireline adapted for use within a tubing string in an earth borehole;

FIG. 2 is an elevational view, partly in cross section, of the apparatus according to the present invention for applying an elastomeric sheath to a wireline as it is being lowered into an earth borehole; and

FIG. 3 is a pictorial view of a portion of the elastomeric sheath in accordance with the present invention.

Referring now to the drawing in more detail, especially to FIG. 1, there is illustrated an earth borehole in the earth 11 having a casing 12 and a tubing string 13 within the cased borehole. A wireline 14 which would normally have an instrument or tool (not shown) at its lower extremity is adapted for being lowered into, or withdrawn from, the tubing 13. For example, a conventional perforating or logging instrument can be attached to the lower end of the wireline 14 whereby such instrument can be caused to traverse the interior of the tubing 13. As is known in the art, the wireline 14 passes over a measuring sheave 15 which is connected to a transmission 16 to drive a recorder 17 within the surface electronics 18 in synchronism with the depth of the instrument attached to the lower end of the wireline 14. The wireline 14 passes over a hoisting drum 19 having slip rings 20 and 21 with electrical conductors 22 and 23, respectively, for passing the electrical information from the conductors within the wireline 14 to the electronics section 18 for recording on the recorder 17, all of which is conventional in the art.

It should be appreciated that the wireline cable 14 itself can be built in various ways, but frequently such cables used in providing wireline services in the oilfield art have a metallic outer sheath and one or more electrical conductors within the center portion of the wireline for transmitting electrical signals to and from the instrument attached at the bottom of the wireline to the earths surface.

Referring now to FIG. 2, there is illustrated in an expanded view the wireline 14 passing over the measuring sheave l5 and down through the tubing 13. As illustrated in FIG. 2, the tubing 13 has a plastic coating on its interior and exterior to prevent the corrosion of such metal tubing from produced fluids from the well and also from injected fluids used in injection and disposal wells.

A platform floor 31 surrounds the plastic coated tubing 30. A support member 32 is mounted on the floor 31 and has thereon a motor-driven drum and hoist unit having a variable speed motor 33 which through a belt drive 34 drives the drum 35 which is used for reeling and unreeling an elastomeric sheath 36. The elastomeric sheath 36, a segment of which is pictorially illustrated in FIG. 3, has a slot 37 along its length and is adapted upon the drum 35 in a manner such that the slot 37 is on the outermost portion of the sheath 36 as the sheath is being reeled or unreeled from the drum 35. The apparatus 32 also includes an orienting finger 38 riding within the slot 37 of the sheath 36 to facilitate the movement of the sheath onto the wireline 14. The

sheath 36 passes over a measuring sheave 39 which produces an electrical signal indicative of the linear velocity of the sheath 36 as it is being applied to, or retrieved from, the wireline 14. The electrical signal from the measuring sheave 39 is transmitted by means of conductor 40 to a conventional electrical comparator circuit 41.

A conventional velocity sensor 42 is used with the transmission 16 to produce a second electrical signal functionally related to the linear velocity of the wireline 14 over the measuring sheave l5 and is transmitted by an electrical conductor 43 to the comparator circuit 41. The electrical output of the comparator circuit 41 is transmitted by conductor 44 to the variable speed motor 33.

Attached to the top of the tubing 13 are two pairs of idler rollers 50 and 51 which are used to guide the sheath 36 along the wireline 14. The support members 52 and 53 associated with the idler rollers 50 and 51 are pivoted, respectively, at points 54 and 55 to allow the idler rollers to be swung back out of place while the instrument attached to the wireline (not shown) is being lowered into the top of the tubing 13 or being removed therefrom.

In the operation of the apparatus described with respect to FIG. 2, it should be appreciated that the idler rollers 50 and 51 are pivoted back out of position and the instrument attached to the bottom of the wireline is allowed to pass down into the tubing 13. Then the rollers are pivoted into place in a surrounding relationship to the wireline 14. The free end of the sheath 36 is then placed in proximityto the wireline l4 and the orienting finger 38 causes the slot 37 to open and thus the sheath 36 envelops the wireline 14. At this point in the process, the motor 33 is in its neutral position and the sheath 36 is hand-wound into place upon the wireline 14 for several feet until the frictional forces between the sheath 36 and the wireline 14 start to pull the drum causing it to rotate. As the wireline is further lowered into the tubing, the sheath 36 follows it along causing the wireline to be enveloped by the sheath. This process continues until the wireline has been extended to its greatest depth within the tubing.

As the wireline is being retrieved, the process reverses itself except themotor 33 is now engaged to drive the hoisting drum 35 and the sheath 36 is wound onto the drum. As the sheath 36 passes over the measuring sheave 39 and as the wireline 14 passes over the sheave 15, electrical signals are produced on the inputs from the electrical conductors 40 and 43 indicative of the individual velocities of the sheath 36 and the wireline 14, and these signals are compared in the electrical comparator 4]. The output appearing on the electrical conductor 44 coupled into the variable speed motor 33 then causes the motor 33 to speed up or slow down, depending upon the comparison, to thus cause the sheath 36 to travel at the same linear velocity as that of the wireline 14.

While the preferred embodiment contemplates that the individual velocities of the sheath and the wireline are compared to drive the motor 33, it should be appreciated by those in the art that a tension sensor can also be used to monitor the tension within the sheath 36 and to thus control the rotational speed of the drum 35 based upon the sensed tension within the sheath 36. In such an instance, the rotational speed of the drum 35 should be just enough to maintain the desired tension within the sheath 36.

Thus, it should be appreciated that there has been illustrated and described herein the preferred embodiments of the present invention and that obvious modifications will appear to those skilled in the art from a reading hereof. For example, the operator of the equipment described herein can'visually monitor the sheath 36 as it is being reeled onto the drum 35 and can manu' ally adjust the speed of the motor 33 as desired. Likewise, instead of monitoring the signals indicative of the wireline passing over the sheave 15, a signal indicative of the rotational velocity of the hoist unit 19 associated with the wireline 14 can be compared with the rotational velocity of the drum 35 to maintain the linear velocity of the elastomeric sheath 36 consistent with the linear velocity of the wireline 14. Furthermore, while electrical signals are contemplated in determining the sheath and wireline velocities, pneumatic signals can also be used. It should also be appreciated by those in the art that the invention described and illustrated herein can also be used in earth boreholes without tubing if desired to apply an elastomeric sheath to a wireline.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for applying an elastomeric sheath to a wireline used in oilfield service operations, comprising:

means to lower said wireline into an earth borehole;

and means to apply said sheath to said wireline as said wireline is being lowered into said earth borehole, said sheath having a slot along its length and said system being further characterized by said means to apply said sheath including an orienting finger arranged to open said slot to facilitate the application of said sheath to said wireline. 2. A system for applying an elastomeric sheath to a wireline used in oilfield service operations, comprising:

means to lower said wireline into a tubing string in an earth borehole; and means to apply said sheath to said wireline as said wireline is being lowered into said tubing string, said sheath having a slot along its length and said system being further characterized by said means to apply said sheath including an orienting finger arranged to open said slot to facilitate the application of said sheath to said wireline. 3. A system for applying an elastomeric sheath to a wireline used in oilfield service operations, comprising:

means to lower said wireline into a tubing string in an earth borehole;

means to apply said sheath to said wireline as said wireline is being lowered into said tubing string;

means for removing said sheath from said wireline as said wireline is being retrieved from said tubing string, said means including means to retrieve said sheath at substantially the same linear velocity as that of the wireline during its retrieval, and including means to generate a first signal functionally related to the linear velocity of said wireline and to generate a second signal functionally related to the linear velocity of said sheath, means to compare said first and second signals to generate a third signal functionally related to said comparison, and means to vary the linear velocity of said sheath in a manner functionally related to said third signal.

4. The system according to claim 3 wherein said signals are electrical. 

1. A system for applying an elastomeric sheath to a wireline used in oilfield service operations, comprising: means to lower said wireline into an earth borehole; and means to apply said sheath to said wireline as said wireline is being lowered into said earth borehole, said sheath having a slot along its length and said system being further characterized by said means to apply said sheath including an orienting finger arranged to open said slot to facilitate the application of said sheath to said wireline.
 2. A system for applying an elastomeric sheath to a wireline used in oilfield service operations, comprising: means to lower said wireline into a tubing string in an earth borehole; and means to apply said sheath to said wireline as said wireline is being lowered into said tubing string, said sheath having a slot along its length and said system being further characterized by said means to apply said sheath including an orienting finger arranged to open said slot to facilitate the application of said sheath to said wireline.
 3. A system for applying an elastomeric sheath to a wireline used in oilfield service operations, comprising: means to lower said wireline into a tubing string in an earth borehole; means to apply said sheath to said wireline as said wireline is being lowered into said tubing string; means for removing said sheath from said wireline as said wireline is being retrieved from said tubing string, said means including means to retrieve said sheath at substantially the same linear velocity as that of the wireline during its retrieval, and including means to generate a first signal functionally related to the linear velocity of said wireline and to generate a second signal functionally related to the linear velocity of said sheath, means to compare said first and second signals to generate a third signal functionally related to said comparison, and means to vary the linear velocity of said sheath in a manner functionally related to said third signal.
 4. The system according to claim 3 wherein said signals are electrical. 